Partial Recall

Sunday

May 25, 2008 at 5:04 AM

Sue Halpern finds out what scientists know about dementia.

Behind all the good-natured joking about “senior moments” lies real frustration and fear. How empowering, then, that we can do something to ward off normal, age-related memory loss: exercise. No, it’s not as easy as popping a pill. But as Sue Halpern reports in “Can’t Remember What I Forgot,” even a few brisk walks per week can have a measurable effect. Exercise promotes the birth of new neurons in the very part of the hippocampus (a brain structure crucial to forming new memories) that begins to malfunction with age. Exercise also counters age-related shrinking of the prefrontal cortex, an area involved in concentration and working memory (as in remembering a phone number long enough to dial).

Of course, if you’re unwilling to exercise for your health, or even to look good in a bathing suit, perhaps you’re still hoping for an easier solution. The problem, Halpern explains, is that solid, peer-reviewed science has not yet proved that anything else works: not herbal supplements, fish oil, vitamin E, almonds, $400 interactive computer software or even crossword puzzles. (After reading her section on blueberries, however, you’ll want to buy them by the bucketful.)

To cut through the hype and confusion, Halpern, whose father had dementia, set out to discover what scientists really know, and how close they are to a drug or therapy that works — either for the pathological memory loss caused by Alzheimer’s, or the “normal” kind that happens inexorably as we age. Her most interesting passages highlight the distinctions between the two. Both ravage the hippocampus; yet a different part of the hippocampus is “broken” in each condition, and different molecules have stopped doing their jobs. “To understand something to the point of being able to fix it you have to get down to the molecular level,” Scott Small, a neurologist at Columbia, tells Halpern. “And that’s where we’re at.”

Yet for a book subtitled “The Good News From the Front Lines of Memory Research,” the hope it contains is markedly thin. Most of this “good news” involves new methods for the early detection of Alzheimer’s, which can offer patients only time to plan for an unavoidable fate.

As part of her research, Halpern volunteered for a host of tests that can help diagnose dementia, including a variety of brain scans. She puts her own process of discovery front and center, reporting on cutting-edge science through the story of her interactions with scientists. Halpern, a nature writer and novelist, seems most at home unfolding a scene in naturalistic detail. The richest material comes from her 2005 New Yorker article about Scott Small’s boss, Richard Mayeux, and his research team’s search for a new gene linked to late-onset Alzheimer’s. Suddenly we’re among gamblers, prostitutes and chickens in the early-morning streets of the Dominican Republic, driving to meet the families with Alzheimer’s whose blood samples will reveal the new risk-factor gene.

Unfortunately, Halpern’s enviable powers of description are often squandered on details that seem off-point. For instance, she gives a blow-by-blow account of her six-hour marathon of memory testing, and of her experience lying prone in each brain scanner. She also walks us down too many blind alleys in her reporting. Consider her enthusiasm for a memory drug being developed at a secretive start-up called Sention. “I was the first writer allowed through the door,” she boasts, exhilarated, describing the history and science behind this “honest-to-God gold mine of a wonder drug” in detail. Next thing we know, Sention has gone out of business.

More troublesome are some of Halpern’s sloppy descriptions of the science itself. She writes that flavanoids, celebrated for their cardiovascular health benefits, are a “class of plants” (in truth, they are chemicals found in plants) and at one point assigns “red wine” to this group. She writes that two human genes — the presenilin genes — cause early-onset Alzheimer’s, but are “carried by only a few hundred families worldwide.” (We all carry the genes; what most of us don’t carry are rare, Alzheimer’s-causing mutations in them.)

Part of Halpern’s self-deprecating charm is that she is one of “us,” the general public, fretting about her lapses in memory and pushing scientists to answer our most pressing questions. But readers may sometimes wish for a more authoritative guide. When Small proposes that the “giant, complex thing called normal memory decline could be accounted for by a single molecule,” Halpern is stunned. If this “renegade idea” is correct, she suggests, Small may set off an explosive scientific revolution à la Thomas Kuhn. Well, perhaps the revolution was not adequately televised, but what Small is proposing is a now-standard idea: that changes to single molecules can radically alter brain function and behavior. (Think of SSRIs, like Prozac, for depression.) He even gives Halpern several examples, ranging from Huntington’s disease to the sexual behavior of male prairie voles.

All told, Halpern sees “many reasons to cheer,” given the “smart and committed people” searching for cures. Still, her book ends with a note of disappointment. When Small announces another incremental breakthrough, Halpern can’t help thinking: “All that work in his lab and, so far, in the clinic, not a lot to show for it.” The book itself is a valuable snapshot in time. It lacks, however, a vivid, overarching narrative that would have maintained its value once the science moves on. In the current glut of books about memory, sad to say, this one is likely to be forgotten.

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